Parameter setting change method and setting apparatus

A parameter setting change method for a system that performs multicast distribution from an information distribution apparatus to a plurality of mobile stations via a relay node is provided. In the method, a parameter adjustment setting apparatus analyzes a data reception state output from the plurality of mobile stations and calculates an information-distribution-apparatus setting-change parameter and a relay-node setting-change parameter for making the data reception state within a predetermined range. Then, when the information distribution apparatus can be set to the information-distribution-apparatus setting-change parameter, the relay node performs setting change to the relay-node setting-change parameter.